Illegal re-entry into the United States by deported immigrants was the crime with the most prosecutions by federal authorities, according to a new report by Syracuse University's Transactional Records Access Clearinghouse (TRAC).

Of the 13,122 federal criminal prosecutions in August, the most recent month for which data was released by the U.S. Department of Justice, illegal re-entry by immigrants accounted for 2,139, the study said.

The next most common category was drug-related crime, which accounted for 1,028 prosecutions. Other crimes near the top of the list were unlawful acts with firearms, bringing in and harboring illegal immigrants, the importation of controlled substances and dealing with materials involving the sexual exploitation of minors, the study said.

Susan B. Long, co-director of TRAC, said the prominence of immigration on the list of the most often prosecuted crimes reflects a dramatic change in enforcement over the last several years.

"It shows the priorities of the federal government right now," Long said. "There's been a huge policy shift, and a definite decision to criminally go after people [for immigration offenses]. More resources have been devoted to immigration enforcement."

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Indeed, the Department of Homeland Security, the parent agency of Immigration and Customs Enforcement -- which deals with arresting and deporting immigrants -- accounts for 56 percent of the prosecutions referred to federal authorities.

"The FBI used to be the top agency that referred cases," Long said, "but no more."

The FBI now accounts for 10 percent of the cases referred for prosecution, the data shows.